Adding Progress bar - Swift - swift

Question

I want to add a Progress bar to a tableViewController.
I have one function called HelpersFunctions which do all the calculation.
The function doCalculation is responsible for the calculation.
So, I add the following notification to doCalculation as follow:
NotificationCenter.default.post(name: .return_progress, object: self)
for i in 1...n1 {
//Do all the calculation
}
So, once I reach NotificationCenter.default.post, it will move to a Tableview Controller called CreateNewElementVC
now, inside the ViewDidLoad, I added the following line:
//progress
NotificationCenter.default.addObserver(self, selector: #selector(showProgress), name: .return_progress, object: nil)
In the same swift file, I added the following:
let container_elementProperty: ProgressBarView = {
let view = ProgressBarView()
view.backgroundColor = UIColor(white: 0, alpha: 0.5)
view.translatesAutoresizingMaskIntoConstraints = false
return view
}()
#objc func showProgress() {
if(progressCounter > 1.0){timer.invalidate()}
print("Step 1")
container_elementProperty.frame = CGRect(x: 100, y: 100, width: 200, height: 200)
container_elementProperty.backgroundColor = UIColor(white: 0, alpha: 0.5)
container_elementProperty.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(handleDismiss)))
let queue = DispatchQueue(label: "queue1", qos: .userInteractive)
queue.async {
print("Step 2")
self.view.addSubview(self.container_elementProperty)
}
//view.addSubview(container_elementProperty)
print("Step 3")
container_elementProperty.progress = progressCounter
progressCounter = progressCounter + progressIncrement
let x1: Float = Float(start_Counting)
let x2: Float = Float(End_Counting)
let xx: Float = x1 / x2 * 100
print("Start at: \(xx) %)")
}
So, first I put all the required data in the CreateNewElementVC, then there is a button called run to do all the calculation and then it will move to another TableViewController with all the result.
So while I am inside the function doCalculation, the progress bar should appear .
In fact, the Progress bar container_elementProperty (UIview) appeared just after the calculation is completed which make the progress bar is useless.
Any idea how to make the View called container_elementProperty UIView to be seen ?
I am close to solve this issue as I can see the progress in the stack as below image, I just want to show this on the screen before completing the calculation.
Why I am not able to put the view on the screen while doing the calculation as you can see that step 2 ran first.
The warning related to this issue is: UIView.addSubview(_:) must be used from main thread only.
A Sample Project can be checked on this link at github.
Appreciate any kind of support.

Answer 1

To simulate a progress, such as a network request you cannot simply do a for loop in the main thread, you should use GCD.
To update the progress of an ongoing action use Delegation, not KVO.
Using global variables makes your code flawed, avoid it!
This is a working version of your code.

Answer 2

# Write By Tushar on 11/02/2021#
import UIKit
class ViewController: UIViewController {
let totalValue:Float = 80.0
var firstNumber:Int? = 0
#IBOutlet weak var progressBar: UIProgressView!
override func viewDidLoad() {
super.viewDidLoad()
progressBar.trackTintColor = .white
progressBar.tintColor = .red
// Do any additional setup after loading the view.
progressBar.setProgress(0.0, animated: false)
}
func setProgress(firstValue:Float){
let processValue = firstValue/totalValue
progressBar.setProgress(processValue, animated: true)
}
#IBAction func btnResetClick(_ sender: UIButton) {
print("Reset Button Clicked")
firstNumber = 0
progressBar.setProgress(0.0, animated: false)
}
#IBAction func btnShowProgressClick(_ sender: UIButton) {
guard let presentValue = firstNumber else { return }
let newValue = presentValue + 1
firstNumber = newValue
setProgress(firstValue: Float(firstNumber!))
}
}